The spatial distribution of galaxies within the cosmic microwave background cold spot in the Corona Borealis supercluster     

Carmen Pilar Padilla-Torres  Carlos M. Gutiérrez  Rafael Rebolo  Ricardo Génova-Santos  José Alberto Rubiño-Martin 《Monthly notices of the Royal Astronomical Society》2009,396(1):53-60

We study the spatial distribution and colours of galaxies within the region covered by the cold spot in the cosmic microwave background recently detected by the Very Small Array interpherometer (VSA) towards the Corona Borealis supercluster (CrB-SC). The spot is in the northern part of a region with a radius  ∼1° (∼5 Mpc  at the redshift of CrB-SC) enclosing the clusters Abell 2056, 2065, 2059 and 2073, and where the density of galaxies, excluding the contribution from those clusters, is approximately two times higher than the mean value in typical intercluster regions of the CrB-SC. Two of such clusters (Abell 2056 and 2065) are members of the CrB-SC, while the other two are in the background. This high-density intercluster region is quite inhomogeneous, being the most remarkable feature a large concentration of galaxies in a narrow filament running from Abell 2065 with a length of ∼35 arcmin (  ∼3 Mpc  at the redshift of CrB-SC) in the SW–NE direction. This intercluster population of galaxies probably results from the interaction of clusters Abell 2065 and 2056. The area subtended by the VSA cold spot shows an excess of faint  (21 < r < 22)  and red  (1.1 < r − i < 1.3)  galaxies as compared with typical values within the CrB-SC intercluster regions. This overdensity of galaxies shows a radial dependence and extends out to ∼15 arcmin. This could be the signature of a previously unnoted cluster in the background.  相似文献   

Combining the standardized precipitation index and climatic water deficit in characterizing droughts: a case study in Romania   总被引：1，自引：1，他引：0  

Cr. Paltineanu  I. F. Mihailescu  Zoia Prefac  Carmen Dragota  Felicia Vasenciuc  Nicola Claudia 《Theoretical and Applied Climatology》2009,97(3-4):219-233

This paper characterizes droughts in Romania using the approach of both the standardized precipitation index (SPI) and climatic water deficit (WD). The values of the main climatic factors (rainfall, temperature, reference evapotranspiration, etc.) were obtained from 192 weather stations in various regions of Romania. Penman–Monteith reference evapotranspiration (ET_o-PM) was used to calculate WD as the difference between precipitation (P) and ET_o-PM. SPI was calculated from precipitation values. There is a clear difference between drought and aridity. Drought occurrence determines higher WD values for plains and plateaus and lower climatic excess water (EW) values for high mountains in Romania, depending on the aridity of the specific region considered and drought severity. WD calculated as mean values for both normal conditions and, for all locations studied, various types of drought was correlated with mean annual precipitation and temperature, respectively. The combined approach of WD and SPI was mainly carried out for periods of 1 year, but such studies could also be done for shorter periods like months, quarters, or growing season. The most arid regions did not necessarily coincide with areas of the most severe drought, as there were no correlations between WD and SPI and no altitude-based SPI zones around the Carpathian Mountains, as is the case for other climate characteristics, soils and vegetation. Water resource problems arise where both SPI values characterize extremely droughty periods and WD values are greatly below ?200 mm/year. This combined use of SPI and WD characterizes the dryness of a region better than one factor alone and should be used for better management of water in agriculture in Romania and also other countries with similar climate characteristics.  相似文献   

Sporadic breakdowns of stability in the PBL over simple and complex terrain     

Carmen J. Nappo 《Boundary-Layer Meteorology》1991,54(1-2):69-87

Breakdowns of stability in the PBL are examined using one-minute average horizontal wind speeds and temperatures observed over many nights at stations located in simple and complex terrain. The analysis is based on the temporal behavior of the wind speed-temperature covariance, which is obtained by digital bandpass filtering. It is shown that breakdowns are a common feature of the stable PBL over both simple and complex environments. Vertical fluxes of heat during breakdowns are estimated to be a significant fraction of the nighttime average heat flux. It is hypothesized that a major portion of the nighttime vertical transfer of heat, momentum, and atmospheric pollutants occurs during periods of stability breakdowns.  相似文献   

The nature and distribution of organic matter in the surface sediments of world oceans and seas     

Eugene T. Premuzic  Carmen M. Benkovitz  Jeffrey S. Gaffney  John J. Walsh 《Organic Geochemistry》1982,4(2):63-77

Existing data on the distribution of organic carbon and nitrogen in marine sediments have been analyzed in order to better understand the physical and chemical processes involved in this aspect of the global carbon cycle. Maps of the global distribution of organic carbon and nitrogen in the sediments of world oceans and seas are presented.Correlation analyses of the available information dealing with the distribution of marine sedimentary organic matter has revealed that in terms of bulk parameters (%C_Org and %N Kjeldahl), there is an apparent accumulation of organic matter on the continental slope (water column depth 200–2000 m). Specific interactions between clays and organic matter, although indicated in laboratory experiments, have not been detected by these analyses.  相似文献   

Further constraints for Permo-Carboniferous magnetostratigraphy: case study of the sedimentary sequence from San Salvador–Patlanoaya (Mexico)De nouvelles contraintes pour la magnétostratigraphie du Permo-Carbonifères : cas d'étude de la séquence sédimentaire de San Salvador–Patlanoaya (Mexique)     

Luis M Alva-Valdivia  Avto Goguitchaichvili  Manuel Grajales  Antonio Flores de Dios  Jaime Urrutia-Fucugauchi  Carmen Rosales  Juan Morales 《Comptes Rendus Geoscience》2002,334(11):811-817

We report rock-magnetic and magnetostratigraphic results from one of the best exposed Permo-Carboniferous outcrops in Mexico, in order to determine some decisive magnetostratigraphy constraints. Some spinels, most probably titanomagnetites, seem to be responsible for aimantation, although greigite may also exist judging from thermal desaimantation of isothermal remanence. Remanence analyses indicate that only one remanent component could be recognized with minor secondary overprint, which were easily removed applying 100–180 °C. Six normal and four reverse magnetozones were recognized from bottom to top in Patlanoya section between 340 and 280 Myr. Both normal and reverse polarity rocks were found in Carboniferous time around 340 Myr, in agreement with previous paleomagnetic works. Our record revealed two normal subchrons within PCRS (Kiaman), the dominantly reverse superchron, at 305 and 280 Myr, respectively. These, which may be speculatively correlated to normal aimantation, occasionally occurred during PCRS interval. More detailed studies are needed in order to establish a more precise magnetostratigraphy for Permo-Carboniferous time. To cite this article: L.M. Alva-Valdivia et al., C. R. Geoscience 334 (2002) 811–817.  相似文献   

Ground Motion Zoning of Santiago de Cuba: An Approach by SH Waves Modelling   总被引：3，自引：0，他引：3  

Leonardo Alvarez  Julio García  Franco Vaccari  Giuliano F. Panza  Bertha González  Carmen Reyes  Bárbara Fernández  Ramón Pico  José A. Zapata  Enrique Arango 《Pure and Applied Geophysics》2004,161(5-6):1041-1059

— The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Oriente fault zone is studied. Synthetic SH-waves seismograms have been calculated along four profiles in the basin by the hybrid approach (modal summation for the path source-profile and finite differences for the profile) for a maximum frequency of 1 Hz. The response spectra ratio (RSR) has been determined in 49 sites, distributed along all considered profiles with a spacing of 900 m. The corresponding RSR versus frequency curves have been classified using a logical-combinatorial algorithm. The results of the classification, in combination with the uppermost geological setting (geotechnical information and geological geometry of the subsoil) are used for the seismic zoning of the city. Three different main zones are identified, and a small sector characterized by major resonance effects, due to the particular structural conditions. Each zone is characterized in terms of its expected ground motion parameters for the most probable strong earthquake (M_S=7), and for the maximum possible (M_S=8).  相似文献   

Influence of Mediterranean sea-level changes on the Dacic Basin (Eastern Paratethys) during the late Neogene: the Mediterranean Lago Mare facies deciphered   总被引：2，自引：0，他引：2  

Georges Clauzon  Jean-Pierre Suc†  Speranta-Maria Popescu†  Mariana Marunteanu‡  Jean-Loup Rubino¶  Florian Marinescu‡  Mihaela Carmen Melinte§ 《Basin Research》2005,17(3):437-462

A recently published scenario viewing the Messinian salinity crisis as two evaporitic steps rather than one has led to a search for new indices of the crisis in the Eastern Paratethys. Fluvial processes characterized the southwestern Dacic Basin (Southern Romania, i.e. the Carpathian foredeep) whereas brackish sediments were continuously deposited in its northern part. This is consistent with previously evidenced responses of the Black Sea to the Messinian salinity crisis. High sea‐level exchanges between the Mediterranean Sea and Eastern Paratethys are considered to have occurred just before and just after desiccation of the Mediterranean. This accounts for two successive Mediterranean nannoplankton‐dinocyst influxes into the Eastern Paratethys that, respectively, belong to zones NN 11 and NN 12. Meanwhile, two separate events that gave rise to Lago Mare facies (with Paratethyan Congeria, ostracods and/or dinoflagellate cysts) arose in the Mediterranean Basin in response to these high sea‐level exchanges and located 5.52 and 5.33 Ma (isotopic stages TG 11 and TG 5, respectively), i.e. just before and just after the almost complete desiccation of the Mediterranean). These Lago Mare facies formed independently of lakes with ostracods of the Cyprideis group that developed in the central basins during the final stages of desiccation. The gateway faciliting these water exchanges is not completely identified. A proto‐Bosphorus strait seems unlikely. A plausible alternative route extends from the northern part of the Thessaloniki region up to the Dacic Basin and through Macedonia and the Sofia Basin. The expression ‘Lago Mare’ is chronostratigraphically ambiguous and should be discontinued for this purpose, although it might remain useful as a palaeoenvironmental term.  相似文献   

Role of biological soil crust cover in bioweathering and protection of sandstones in a semi‐arid landscape (Torrollones de Gabarda,Huesca, Spain)     

Virginia Souza‐Egipsy  Jacek Wierzchos  Carlos Sancho  Anchel Belmonte  Carmen Ascaso 《地球表面变化过程与地形》2004,29(13):1651-1661

Sandstone structural landscapes in the semi‐arid Torrollones de Gabarda area (Province of Huesca, NE Spain) are often covered by a well developed biological soil crust of lichens, mosses and cyanobacteria and black coatings on vertical surfaces. By using scanning electron microscopy with backscattered detector imaging, the biological soil crust studied evidenced high activity in the sandstone–crust interface. Processes such as physical disintegration, etching and dwelling as well as biomineralization by calcium oxalate and ?xation of mineral particles by extracellular polymeric substances were observed. On the horizontal sandstone surfaces these processes may cause the occurrence of gnammas and the development of a protective coating that favours intense ?aking when the crust is disturbed. On the sandstone cliffs, columnar and tafoni weathering development is clearly guided by the protective action of the biological soil crust. These qualitative observations are important to develop methodologies to address their quantitative importance in geomorphological processes in semi‐arid landscapes. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Seasonal fluctuations in the plankton community in a hypersaline temporary lake (Honda, southern Spain)     

Pablo J. López-González  Francisco Guerrero  M. Carmen Castro 《International Journal of Salt Lake Research》1997,6(4):353-371

Honda saline lake is located in an endorheic basin in the south of Spain. The lake is very shallow, with frequent seasonal drought and a high degree of unpredictability. It was sampled monthly during a relatively dry year (1994–1995, 5 months permanence). To establish a relationship between environmental variables (temperature, depth, salinity and conductivity), variables related to biological activity (organic matter, total solids suspension, and pH) and the planktonic community in the sampled months, various uni-and miltivariate statistical methods were carried out.Dunaliella salina, D. viridis, and ciliates sp. 2 is the principal species group used to average out the dissimilarity between the samples. Muttivariate analysis showed that salinity (as TDS), conductivity and pH made major and significant contributions to the explanation of the variance in the sample data.  相似文献   

Networking for Local Agenda 21 implementation: Learning from experiences with Udaltalde and Udalsarea in the Basque autonomous community     

José M. Barrutia  Carmen Echebarria 《Geoforum》2007,38(1):33-48

Local Agenda 21 (LA21) is widely regarded as a key tool for implementing sustainability policies since local authorities are closer to ordinary people and some local managers and politicians have the ability to adapt organisations to new managerial atmospheres and social demands. However, local governments tend to lack the right economic, human and knowledge resources. Consequently, in the search for local sustainable development, networking and collaborative approaches to LA21 can help local authorities save resources and share knowledge and best practices. Although both research and politicians have tended to focus on LA21, we believe Regional Agenda 21 (RA21) needs to be emphasised as a complementary tool. This paper examines successful innovative practices in the Basque Autonomous Community (BAC) over a 4-year period, with a view to shedding light on the theoretical literature and to aiding regional and local authorities. Although research on policy networks has produced useful results, we are still some way from a plausible, consensus-based theory of policy networks. Based on experience in the BAC, the present article offers an integrated approach to understanding the antecedents and consequences of a regional knowledge-driven network for LA21 promotion. Although LA21 implementation has been studied before, evidence about networking at regional level is scarce. Other regions in developing countries could use this approach to achieve successful policy networks.  相似文献